primary ciliary dyskinesia

Primary ciliary dyskinesia, or PCD, is an inherited disease in which the body's cilia are built wrong and cannot beat properly. Because the airways rely on those beating hairs to sweep mucus out, people with PCD have a clearance system that is broken from birth, so mucus and germs collect and infections keep returning.

The fault lies in the genes that build the cilium's internal motor and scaffold. When the motor proteins or supporting structures are defective, cilia may be immotile, beat weakly, or beat in an uncoordinated way. The consequences begin early: chronic wet cough, recurrent ear and sinus infections, persistent nasal congestion, and over time the airway widening and scarring of bronchiectasis.

Because the same kind of cilia also guide organ placement in the embryo and propel sperm and egg, PCD often comes with situs inversus (mirror-image internal organs) and reduced fertility — the classic triad with sinusitis and bronchiectasis is called Kartagener syndrome. There is no cure, but airway clearance physiotherapy, prompt treatment of infections, and monitoring of lung function help preserve breathing over a lifetime.